Implement Curation Cache

[kkaris]

When loading a page that needs curations, the web app currently loads all curations every time. This operation takes one to a couple of seconds and adds to a slower load time. We should implement some type of curation cache that fulfills the following:

• Load the cache when starting the app
• By default, a page that needs curations loads them from the cache
• When e.g. a curation page reloads to get the next round of curations, the cache would update
• After a certain time the cache could update on its own

Long term:

• Consider caching the curations on the frontend as well. This could pave the way for doing a more dynamic page that can show/hide curated content with a toggle rather than reloading the page.

[kkaris]

Resolved in #92